1. Field of the Disclosure
The disclosure relates generally to techniques for measuring pulse timing based events and, more particularly, to techniques for resolving pulse times measurements at small scale times.
2. Brief Description of Related Technology
It is challenging to directly measure of the mass and velocities of atoms, molecules and larger-scale microscopic particles. Time of flight (TOF) techniques can identify particles (or other triggering events) by measuring the time it takes a particle to travel a particular distance. These techniques can be used to measure properties like mass and velocity that are correlated to travel time. Intuitively this makes sense, because particles of lower mass with a given energy will typically traverse the same flight path in a shorter period of time than particles of higher mass. TOF techniques, for example, are used in mass spectroscopy to measure the velocity of a particle as it moves through a known distance, and then correlating that velocity to a mass from which the particle may be identified.
Because TOF techniques are effective in measuring characteristic properties of particles, the techniques are useful in atmospheric and space applications where particle detection can be performed under diverse, often very challenging conditions. TOF mass spectrometers have been used in space application as part of a plasma imaging spectrometer that measures particle count rates, energy distributions, velocity vector distributions, and mass spectra, and do so at high time resolutions and with relatively low electron volt energies.
TOF techniques are used in other chemical and biological applications in combination with other techniques, such as gas-chromatography and fast kinetic processes measurements such as ion movement. More generally, TOF techniques fit within a category of techniques that use time measurements between triggering events (START and STOP events) to analyze some phenomena. Highly accurate timing measurements, for example, are used in circuit design to test the propagation of signals through digital and analog circuits as part of automatic circuit testing equipment.
While highly accurate timing techniques for TOF and other applications are known, those techniques typically require substantial computing power, or, are performed in application specific circuits. In fact, timing circuits generally are developed using an integrated circuit with phase-lock loops, delay-locked loops, and serial/deserializers. TOF applications are typically implemented through an application specific integrated circuit (ASICs) or a microprocessor. These options are costly and can require substantial development time, especially for applications where the time scales become very small, for example, on the order of a 100 picoseconds or less. Furthermore, such circuits have a substantial environmental imprint, and thus are particularly disadvantageous in spacecraft applications where space and available power are at a premium. The circuits are designed for one specific application and it is rather difficult to apply them from one application to the next, without going through the same process. Finally, it is rather difficult to package integrated circuits in radiation protected configurations, as would be required for proper operation in space applications. In fact, because of the limitations on TOF circuits, only a few TOF circuits (and very expensive ones) have been rated “space qualified.”
Thus, there is a need for lower cost, efficient timing circuits having time scales short enough to allow for useful time of flight applications, in space and other applications.